Re: [PATCH] target/i386: relax assert when old host kernels don't include msrs

[Catherine Ho]

Hi Paolo

[sorry to resend it, seems to reply it incorrectly]

On Wed, 4 Dec 2019 at 19:23, Paolo Bonzini <address@hidden> wrote:

On 04/12/19 09:50, Catherine Ho wrote:
> Commit 20a78b02d315 ("target/i386: add VMX features") unconditionally
> add vmx msr entry although older host kernels don't include them.
>
> But old host kernel + newest qemu will cause a qemu crash as follows:
> qemu-system-x86_64: error: failed to set MSR 0x480 to 0x0
> target/i386/kvm.c:2932: kvm_put_msrs: Assertion `ret ==
> cpu->kvm_msr_buf->nmsrs' failed.
>
> This fixes it by relaxing the condition.

This is intentional.  The VMX MSR entries should not have been added.
What combination of host kernel/QEMU are you using, and what QEMU
command line?

Host kernel: 4.15.0 (ubuntu 18.04)

Qemu: https://gitlab.com/virtio-fs/qemu/tree/virtio-fs-dev

cmdline: qemu-system-x86_64 -M pc -cpu host --enable-kvm -smp 8 \
                  -m 4G,maxmem=4G

But before 20a78b02d315, the older kernel + latest qemu can boot guest

successfully.

Best Regards,

Catherine